Cyrtodactylus chanhomeae, Bauer, Aaron M., Sumontha, Montri & Pauwels, Olivier S. G., 2003

Bauer, Aaron M., Sumontha, Montri & Pauwels, Olivier S. G., 2003, Two new species of Cyrtodactylus (Reptilia: Squamata: Gekkonidae) from Thailand, Zootaxa 376, pp. 1-18 : 9-15

Cyrtodactylus chanhomeae sp. nov.

Figures 4–6 .

Holotype.— Institut Royal des Sciences Naturelles de Belgique ( IRSNB) 2585 (formerly CUMZ R 2003.61), adult male; Thailand, Saraburi Province, Phraputthabata District, Khun Khlon Subdistrict, Phraya Chat­tan Cave, 14°42’N 100°51’E; collected by Montri Sumontha, 23 May 2003 (16:30).

Paratype.— Chulalongkorn University Museum of Zoology ( CUMZ) R 2003.62, adult male; Thailand, Saraburi Province, Phraputthabata District, Khun Khlon Subdistrict, Thep Nimit Cave; 14°42’N 100°51’E; collected by Montri Sumontha, 23 May 2003 (15:50).

Etymology. — The specific epithet is a matronym honoring Dr. Lawan Chanhome of the Queen Saovabha Memorial Institute of the Thai Red Cross Society, Bangkok. Dr. Chanhome has been and continues to be an active contributor to the study of Thai venomous snakes. The epithet is formed in the feminine genitive.

Definition. — A moderately sized Cyrtodactylus , snout­vent length to at least 79 mm; body slender, limbs and digits long, slender; one pair of enlarged postmental scales in broad contact with one another; dorsal scalation with 16­18 rows of keeled tubercles; 36– 38 ventral scales across belly between ventrolateral folds; no precloacal groove, a continuous series of 32–34 pore­bearing precloacal­femoral scales (at least in males). 7–9 broad basal lamellae and 14 narrow distal lamellae beneath 4th toe of pes. Median subcaudal scales enlarged to form broad transverse plates. Dorsal pattern of purplish brown bands, bordered anteriorly and posteriorly by yellowish­cream bands; 3 such bands on trunk and a fourth on nape and occiput.

Description (based on holotype, IRSNB 2585). — Adult male. Snout­vent length 69.90 mm. Head long (HeadL/SVL ratio 0.30), relatively narrow (HeadW/HeadL ratio 0.61), somewhat depressed (HeadH/HL ratio 0.36), distinct from slender neck. Lores and interorbital region weakly inflated, canthus rostralis not especially prominent, frontonasal region strongly concave. Snout elongate (SnEye/HeadL ratio 0.40), pointed; longer than eye diameter (OrbD/SnEye ratio 0.63); scales on snout and forehead small, rounded, granular, homogeneous; scales on snout larger than those on occipital region. Eye large (OrbD/ HeadL ratio 0.26); pupil vertical with crenelated margins; supraciliaries short, bearing minute conical spines posteriorly. Ear opening oval, relatively large (EarL/HeadL ratio 0.06); eye to ear distance much less than diameter of eye (EyeEar/OrbD ratio 0.80). Rostral 61% deep (1.76 mm) as wide (2.88 mm), incompletely divided (40%) dorsally by rostral groove; two enlarged supranasals in broad contact; rostral in contact with supralabial I and supranasals only; nostrils round, each surrounded by supranasal, rostral, first supralabial, and two enlarged postnasals; a valvular projection occupies posterior half of nostril; 2–3 rows of small scales separate orbit from supralabials. Mental triangular, wider (3.60 mm) than deep (2.58 mm); one pair of enlarged postmentals, each bordered anteromedially by mental, medially in broad contact with other postmental, bordered anterolaterally by first infralabial, laterally by second infralabial, posterolaterally by 2 enlarged lateral chinshields, and posteriorly by 3 slightly enlarged chin granules. Supralabials to midorbital position 9 (right) to 10 (left); enlarged supralabials to angle of jaws 12 (right) to 13 (left); infralabials 9 (right) to 10 (left); interorbital scale rows across narrowest point of frontal bone 16.

Body slender, relatively short (TrunkL/SVL ratio 0.38) with very weakly demarcated, non­denticulate ventrolateral folds. Dorsal scales granular to weakly conical; regularly distributed tubercles (3–4 times size of adjacent scales) extending from occipital region on to back and tail base; each tubercle conical, forming a weak keel on the anterior­facing surface, especially in middorsal tubercle rows; tubercles in approximately 18 rows at midbody, absent from flanks. Ventral scales much larger than dorsals, smooth, hexagonal, and subimbricate, largest posteriorly; midbody scale rows across belly to base of ventrolateral folds 38; gular region with relatively homogeneous, smooth scales. Continuous series of 32 precloacal and femoral pores; femoral scales greatly enlarged; no precloacal groove ( Fig. 5 ). Scales on palm and sole smooth, rounded; scalation on dorsal aspects of hindlimb heterogeneous, with enlarged, weakly conical tubercles interspersed among smaller scales; forelimbs with tubercles less well developed.

Fore and hindlimbs long, slender (ForeaL/SVL ratio 0.18; CrusL/SVL ratio 0.23); digits long, slender, strongly inflected at interphalangeal joints, all bearing robust, slightly recurved claws; basal subdigital lamellae nearly as broad as digit, oval to rectangular, without scansorial surfaces (5–7–7–6–6 manus; 5–7–7–7–8 pes); narrow lamellae distal to digital inflection and not including ventral claw sheath: 10–11–14–12–12 (manus), 12– 12–15–14 –15 (pes); interdigital webbing absent. Relative length of digits (manus; measurements in mm in parentheses): III (8.08) ~ IV (8.05)> II (7.51) = V (7.51)> I (5.80); (pes): IV (9.71)> V (8.76)> III (8.51)> II (8.10)> I (5.63).

Partly regenerated tail slender, gently tapering to tip; slightly longer than snout­vent length (TailL/SVL ratio 1.06); original portion of tail distinctly segmented; each segment 9 dorsal scale rows in extent; dorsal caudal scales flat, smooth, rectangular, homogeneous except for basal segments where 6 parasagittal rows of enlarged, weakly keeled tubercles continue from the body dorsum to the last pygal segment; ventral scales smooth, greatly enlarged transversely, extending the entire width of the tail venter; two such transverse plates per tail segment. Series of 4 small, smooth, conical postcloacal spurs on each side of tailbase.

Osteology: Parietal bones paired; stapes imperforate. Phalangeal formula 2–3–4–5–3 for manus and 2–3–4–5–4 for pes. Presacral vertebrae 26, including 3 anterior cervical (without ribs), 2 lumbar (one in paratype), and 2 sacral vertebrae; 5 pygal and 18.5 post pygal caudal vertebrae to point of regeneration in holotype (0.5 post­pygal vertebrae in paratype). Both specimens with one pair of crescentic cloacal bones present, flared both medially and laterally. Endolymphatic sacs not enlarged extracranially. Long bones of holotype with incomplete fusion, suggesting it may be a subadult or if mature, that it has not reached maximum size. Those of paratype fused.

Coloration (in preservative): Base color a pale brown. Banded with mid brown markings, each with a darker brown posterior border; each such band bordered anteriorly and posteriorly by a thinner cream band; 3 sets of such alternating bands between limb insertions and one across sacrum. Dorsal pattern faded on flanks. Alternating light and dark pattern of dorsum continues on to tail. 11 dark bands on original portion of tail. Distalmost part of tail very pale ( Fig. 4 ). A prominent brown collar with darker margins from posterior border of orbits through dorsal half of ear and across nape continuing anterior of orbits to nostril. Dorsum of head pale yellow with scattered, slightly darker, diffuse markings at anterodorsal margin of orbits and on parietal. A light line bordering nape band extends from frontonasal area through dorsal part of eye to quadrate and on to occiput. Labial scales beige with scattered brown punctations. Limbs pale brown, weakly marked by darker mottling and scattered irregular white markings, especially distally. Venter cream to beige.

Color in life much bolder ( Fig. 6 ), dark bands purplish brown, paler bands yellowishcream, somewhat brighter yellow on head and tail. Venter pale brown. Iris greenish brown.

Variation. — Comparative mensural data for the holotype and paratype are presented in Table 1 . The paratype is similar to the holotype in most respects except as noted. CUMZ R 2003.62: Adult male. Rostral crease “Y” shaped. Postmentals bordered posterolaterally by a single enlarged lateral chinshield and posteriorly by 2–3 slightly enlarged chin granules; 9 supralabials to middle of orbit, 12 (left) to 13 (right) enlarged supralabials to corner of mouth; 10 infralabials. 18 interorbital scale rows across narrowest point of frontal bone. Tubercles in approximately 16 longitudinal rows at midbody; midbody scale rows across belly to base of ventrolateral folds 36. Precloacal­femoral pores in single series of 34, with one poreless scale separating 5 most distal pores on right thigh from remainder of series.

Enlarged basal subdigital lamellae 5–6–7–7–7 (manus), 6–7–7–9–7 (pes); narrow lamellae distal to digital inflection and not including ventral claw sheath: 12–12–13–13 –13 (manus), 12–13–14–14 –16 (pes). Transversely widened subcaudal plates evident even on regenerated portion of tail. Color pattern similar to holotype, but head markings more pronounced.

Diagnosis. — Cyrtodactylus chanhomeae may be distinguished from all congeners on the basis of the following combination of characters: body slender, limbs and digits long, dorsal scalation with 16–18 rows of keeled tubercles, 36–38 ventral scales across belly between ventrolateral folds, no precloacal groove, a continuous series of 32–34 pore­bearing precloacal­femoral scales (at least in males), median subcaudal scales enlarged to form broad transverse plates, and dorsal pattern of purplish brown bands, bordered anteriorly and posteriorly by yellowish­cream bands (5 such pale bands between limb insertions).

On the basis of its continuous single series of precloacal and femoral pores and absence of a precloacal groove, Cyrtodactylus chanhomeae may be distinguished from C. tigroides and the majority of its other congeners (refer to Diagnosis of C. tigroides ). Among those species with a continuous series of pores (or for which this condition could not be adequately assessed based on literature and specimens available to the authors), the new species may be distinguished from the Pacific species C. abrae , C. derongo , C. loriae , C. louisiadensis , C. novaeguineae , and C. tuberculatus on the basis of its much smaller size (to 79 mm SVL for types vs.> 110 mm SVL), as well as lower ventral scale counts and coloration differences. It may be distinguished from C. papilionoides and C. malcolmsmithi by its greatly expanded subcaudal plates, which extend the entire width of the tail, from C. darmandvillei by its much smaller and less coarse dorsal tubercles, from C. jarujini by its lower number of pores (32 vs 52) and banded rather than spotted or blotched pattern, from C. variegatus by its greater number of midventral scale rows (36–38 vs 22), from C. tiomanensis and C. phongnhakebangensis by its greater number of pale bands (4– 5 vs 3) between limb insertions, and from C. feae by its lack of a well­defined reticulate pattern on the dorsum of head.

Distribution and Natural History.— Cyrtodactylus chanhomeae has thus far been found only in and around caves in the Phraputthabata District (Khun Khlon Subdistrict) of Saraburi Province in central Thailand, north of Bangkok.

Three male specimens of C. chanhomeae were found by day on the walls of limestone caves, 10­20 m from the cave mouth in near total darkness, at heights of 0–3 m above the ground (where cave ceiling was 2–8 m). At night, one female was found inside a cave, and a juvenile was found outside the cave entrance (19:20, 23 May 2002). Others were seen inside caves between 22:00 and 0:30 (30–31 May 2003). Other gecko species found in the vicinity of the type locality were Gekko siamensis Grossmann & Ulber , Gehyra cf. fehlmanni (Taylor) , and Dixonius melanostictus (Taylor) . The first two of these were observed both inside and outside the caves. Several specimens of C. chanhomeae were kept alive in captivity for some time. During this time they readily accepted crickets and meal worms and bit if handled roughly. The species is able to jump quite long distances, but does not run quickly.

Figures

FIGURE 4. Holotype (IRSNB 2585) of Cyrtodactylus chanhomeae, sp. nov. from Phraya Chat­tan Cave, Phraputthabata District (Khun Khlon Subdistrict), Saraburi Province, Thailand. Note the elongate limbs and digits, and conspicuous dorsal markings. Photo by Aaron M. Bauer.

FIGURE 5. Male holotype of C. chanhomeae, sp. nov. The black line parallels the pore­bearing scales of the left side of the animal’s body. Note the continuous series of precloacal and femoral pores, enlarged femoral scales, and transversely widened subcaudal plates. Photo by Aaron M. Bauer.

FIGURE 6. Adult male holotype of Cyrtodactylus chanhomeae, sp. nov. (IRSNB 2585) in life. Note the large eyes and pale yellowish markings. Photo by Lawan Chanhome.